Prepare and marinate the chicken. In a medium bowl whisk together the marinade ingredients until fully combined (Greek yogurt, olive oil, lemon juice, minced garlic, garam masala, ground ginger, ground cumin, sweet paprika, turmeric, salt, and pepper). Add the chicken to the marinade mixing well to coat. Cover and transfer to the refrigerator to marinate for at least 30 minutes or up to 2-3 days.
Prepare the Curry Yogurt Sauce. Add the ingredients for the Curried Yogurt Sauce (plain Greek yogurt, chopped cilantro, parsley, garlic, lemon juice, olive oil, curry powder, salt, and pepper) to the bowl of a small food processor. Pulse 4-5 times, remove the lid, scrape down the sides, and pulse 3-4 more times, or until desired consistency is reached. Season with additional curry powder, salt, and pepper, to taste. Cover and transfer to the refrigerator until ready to enjoy.
Prepare the Cucumber, Tomato, and Pomegranate topping - chop the tomatoes, cucumber, and white onion into small, approximately equal-sized pieces. Transfer to a medium bowl. Add the pomegranate arils, avocado, and gently mix with the juice from half a lemon (see notes).
Cook the chicken. Heat 1 tablespoon of oil in a large heavy-bottomed skillet over medium-high heat. Swirl to coat the bottom of the pan. Add the chicken pieces to the hot skillet in a single layer, working in batches if necessary (gently shake off excess marinade before adding the chicken to the pan). Allow the chicken to cook, undisturbed, for 3 minutes, Quickly stir and continue to cook an additional 3-5 minutes, or until the chicken is golden brown and cooked through.
Assemble. Place desired amount of curry yogurt sauce on top of a soft pita or flatbread and top with 4-5 spices of cooked chicken. Top with a generous spoonful or two of the cucumber, tomato, and pomegranate topping and a fresh squeeze of lemon juice, if desired.